Ingredients:

  • 1 cup (225g) unsalted butter, softened
  • 1 cup (200g) granulated white sugar
  • 1 cup (215g) packed light brown sugar
  • 1 cup (250g) creamy peanut butter
  • 2 large eggs, room temperature
  • 1 tsp pure vanilla extract
  • 2 cups (250g) all-purpose flour
  • 1 tsp baking soda
  • 0.5 tsp fine sea salt
  • 0.5 cup (115g) unsalted butter (for frosting)
  • 0.25 cup (60ml) whole milk
  • 3 tbsp unsweetened cocoa powder
  • 2 cups (240g) powdered sugar, sifted
  • 1 tsp pure vanilla extract (for frosting)

Instructions:

  1. Preheat your oven to 350°F (175°C). Line a 9x13 inch baking pan with parchment paper, leaving an overhang on the sides for easy removal.
  2. In a large mixing bowl, cream together 1 cup softened butter, granulated sugar, and light brown sugar using a hand or stand mixer until the mixture is pale and fluffy, approximately 3 minutes.
  3. Add the creamy peanut butter, eggs, and 1 teaspoon of vanilla extract. Beat on medium speed until the mixture is fully emulsified.
  4. In a separate bowl, whisk together the flour, baking soda, and salt. Gradually fold these dry ingredients into the peanut butter mixture until no flour streaks remain.
  5. Spread the batter evenly into the prepared 9x13 pan. Bake for 18–22 minutes until the edges are light golden brown and the center is set but still slightly soft.
  6. While the bars are baking, prepare the frosting: In a medium saucepan, combine 0.5 cup butter, milk, and cocoa powder. Bring to a brief simmer, then remove from heat. Whisk in the powdered sugar and 1 teaspoon of vanilla until smooth.
  7. Pour the warm chocolate frosting over the peanut butter bars immediately after removing them from the oven. Spread evenly to the edges. Allow the bars to cool completely to let the frosting set before slicing into 24 squares.